Abstract: A large number of terminals are connected to a central computer in a loop utilizing a very high speed transmission medium. A sequential stream of message blocks are provided for transmission by the loop. Each message block includes a first portion specifying a terminal address, and a second portion for specifying information data. Each terminal interrogates the address portion of each message block and responds to its own address by either reading the data portion of the message block or loading into the data portion messages to be transmitted. By generating a continuous stream of message blocks, one for each terminal, and using a randomizing scheme for address generation, it is possible to connect a large number of terminals to a data communications system while maintaining a reasonable response time.